Dual-clutch transmissions — DCTs to their friends — are pretty impressive pieces of technology. Sort of a cross between a regular old bolt-action manual and an automatic, a DCT uses two clutches (natch) to shift between gears. One clutch runs the even-numbered gears, the other the odd-numbered gears, and the driver can typically choose between “manual” mode that lets them select gears or they can let the transmission shift itself. Either way, the twin clutch setup speeds up shifting because while one gear is working, the transmission cues up the next gear in line so that the shift is quick and seamless.
DCTs are well suited to performance applications, where the quick and precise shifting and the pre-selected gear allow a driver to upshift without letting off the throttle. They’re especially good for turbocharged vehicles where they can shift without the engine losing boost. This is why you typically see DCTs in bleeding edge, eye-wateringly expensive, high-performance supercars like Porsches and Ferraris — though they have been used in more workaday cars like Volkswagens and Skodas. Even some motorcycles, like Honda’s Gold Wing, use a DCT.
Now, if you’re thinking that a high-tech and specialized a piece of equipment as a dual-clutch transmission probably needs a high-tech and specialized kind of transmission fluid, you’d be right! Let’s talk about this super special DCT oil, shall we?
A special kind of fluid for a special kind of transmission
As stated, a dual-clutch transmission needs a special kind of transmission fluid. Much like a DCT is a manual/automatic transmission hybrid, DCT fluid is a kind of cross between automatic transmission fluid and heavy gear oil. A good DCT oil needs to have the lubricating and wear-resistant qualities of gear oil and the friction enhancing elements of automatic transmission fluid, while being better and working harder than both. These elements are combined in a way that keeps the complex systems inside a dual-clutch transmission working at peak efficiency.
Can you use automatic transmission fluid or gear oil in a dual-clutch transmission? Not if you want your DCT to last. Using non-DCT fluid in your dual-clutch transmission will cause all kinds of problems ranging from excess noise and hard shifting to excessive wear, overheating, and even, eventually, catastrophic failure. You don’t want to have to shell out a few grand on a new transmission just because you tried to save a few pennies by putting ATF in your fancy DCT, do you? Of course not, so do yourself a favor — stick with the manufacturer’s recommended DCT fluid.